The power density and thermal specification of present high performance processor integrated circuits (ICs) has been driving up the cost and performance of their corresponding heat sink assemblies. As a result, heat sink technology as well as the thermal interface material required between the heat sink and a corresponding integrated circuit have changed. Current thermal solutions used for high performance IC processors require the use of semi-viscous thermal greases to increase thermal conductivity between the IC and its heat sink. These thermal greases create manufacturing problems as well as human factor concerns.
Typically, a heat sink assembly is supplied from a heat sink vendor with a controlled amount of thermal grease applied to the base of the heat sink. The thermal grease may have a specification that requires the thickness of the thermal grease to be 0.005 inch thick with a variation of plus or minus 0.001 inch. The system assembly vendor doing the final board assembly and test would normally attach the heat sink to a corresponding IC. While applying a thickness of thermal grease to the heat sink with high accuracy may be easy to achieve at the heat sink vendor's manufacturing line, any rework required at the system assembly vendor or later in the field makes reproducing the required thermal grease thickness very difficult.
There is, therefore, a need for a method and apparatus that enables a controlled thickness of thermal grease to be applied to a heat sink without resorting to complex equipment or sending the heat sink back to the heat sink vendor for rework.